title: Effect of transfusion therapy on transcranial Doppler ultrasonography velocities in children with sickle cell disease.
abstract: BACKGROUND
  Children with sickle cell disease (SCD) and abnormal transcranial Doppler (TCD) ultrasonography have a high risk of stroke, but this risk is greatly reduced when chronic transfusion therapy is administered. The change in TCD velocities during chronic transfusion therapy and rate and frequency of normalization of TCD findings have not been studied extensively.
  
  
  METHODS
  Using data from children with SCD enrolled as potential subjects in the Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) trial, we characterized the change in TCD velocities on transfusion therapy and identified predictors of developing a normal TCD.
  
  
  RESULTS
  Among 88 children with serial TCD data after starting transfusions for abnormal TCD 46 (52%) converted to normal TCD after a mean of 4.3 months (median 3.0; range 0.85-14.3 months) of transfusions. TCD studies remained abnormal in 19/88 (21.6%) after a mean of 2.4 years of transfusion. The median TCD velocity was lowered by 38 cm/sec within 3 months of initiating transfusions, followed by a more gradual decline then stabilization of velocities, although with significant individual variation. Factors associated with conversion to normal TCD included lower initial TCD velocity, younger age, and higher pre-transfusion hemoglobin level during transfusion therapy.
  
  
  CONCLUSIONS
  Younger children with higher pre-transfusion hemoglobin levels and lower abnormal TCD velocities are most likely to have rapid normalization of TCD on transfusions. Long-term follow-up of children with persistently abnormal exams or worsening velocities on transfusion is needed to determine if these children are at higher risk of stroke.
authors.affiliation: Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA. kwiatkowski@email.chop.edu
authors.forename: Janet L
authors.initials: JL
authors.lastname: Kwiatkowski
authors.forename: Eunsil
authors.initials: E
authors.lastname: Yim
authors.forename: Scott
authors.initials: S
authors.lastname: Miller
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Adams
mesh_terms: D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001783:Blood Flow Velocity; D001803:Blood Transfusion; D002560:Cerebrovascular Circulation / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D020521:Stroke / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000517:prevention & control; D017585:Ultrasonography, Doppler, Transcranial; D055815:Young Adult